I took my marketing classes for my business degree in the early 2000s. Digital marketing was not addressed. The advice at the time was to get to six "impression

I took my marketing classes for my business degree in the early 2000s. Digital marketing was not addressed. The advice at the time was to get to six "impressions," six encounters with your brand before most people would start to recognize the brand. And it was very much admitted that you don't get to measure this and you must correlate sales trends with marketing trends. Very much "gut feel" in comparison of digital tracking. I'm still not convinced the tracking makes that big of a difference but obviously the market disagrees with me.